Modern day workers are required to operate equipment which is becoming increasingly more sophisticated. Each new generation of equipment demands a higher degree of operator skill. Consequently human operators are being asked to perform with increased competency, under greater stress, and with a smaller margin of error than ever before. This is particularly true in occupations involving the operation of computerized heavy equipment, high speed vehicles and other semi-automatic man/machine systems. And while the contemporary work place requires maximum performance, employers are finding that many workers are performing below their capability, and in some cases in an unsafe manner due to impairment by alcohol and drugs as well as other causes.
Estimates of the contribution of drug or alcohol impairment to industrial accidents range as high 50%. Vigorous education programs to ensure a drug-free work place have been instituted. Random biotesting has been undertaken as a supplement to education programs, with mixed levels of success. The difficulty with biochemical tests is that they merely establish that something is in the blood or urine. They do not establish that the chemical is impairing the performance of the person who has been tested. For this reason, biochemical tests are subject to varying court challenges. A further problem with biochemical testing is that it is expensive and time consuming and consequently limited to use on a relatively infrequent basis. Recent developments in a number of areas have resulted in the suggestion that behavioral tests may be more job-relevant, less invasive, more cost efficient and most importantly, equally or more valid in detecting drug, alcohol, and other causes of impairment.
A need therefore exists for an efficient and reliable test which addresses performance degradation generally, regardless of the degradation cause. Such a test should evaluate performance ability relevant to job requirements and to past performance of the individual being tested. A test of that type could be administered to large numbers of persons on a relatively frequent basis and could be complemented by chemical testing where warranted by an observed performance impairment.
The prior art teaches a number of techniques for testing human performance ability. For example, Smith et al. U.S. Pat. No. 4,983,125 discloses a device for measuring the ability of a human operator to stabilize an inherently unstable system. The Smith et al. device requires an operator to maintain a marker within predetermined limits on a moving track. A training period is provided during which the operator learns how to control the marker. In the Smith et al. device the difficulty is automatically increased at a relatively fast rate until the operator approaches the limits of his ability.
Another prior art teaching is shown in Abernethy et al U.S. Pat. No. 3,918,176 which discloses an intoxication testing system including means for simultaneously producing a pair of varying displays. A person being tested, selectively operates a pair of actuators in an attempt to track targets in the two displays. An analyzer measures and records the tracking errors. The subject is also required to watch a light which is periodically energized and to respond by actuating a switch. The switch actuation time is combined with the measured tracking error to provide a measurement of the intoxication level of the person being tested.
Another prior art performance testing device is disclosed in Slomski U.S. Pat. No. 4,006,539. The Slomski device tests the alertness and perception speed of the subject. Slomski's equipment tests psycho-physiological functions, primarily responsiveness to a visual stimulation. The device emits flash signals at different locations and for different durations of time. The subject's reaction to the flashing lights is used as a measure of performance.
A further example of the prior art is shown in Ashkenas et al. U.S. Pat. No. 3,483,302 which discloses a performance testing system wherein the subject performs a tracking operation within a feedback loop having a variable gain. The system is inherently unstable, and the test effectively measures the operator's ability to stabilize the loop.
The prior art also includes a performance testing system as described in Greenberg et al, U.S. Pat. No. 5,103,408. That system tests attention allocation ability by displaying two tasks simultaneously on a monitor together with an arrow indicating which task is to be performed. One task requires the subject to determine the orientation of an object while the other requires recognition and memorization of an alphanumeric character. After the subject has performed one of the tasks, the monitor displays two more tasks along with another indicating arrow. A series of such displays are presented, and a score is assigned for each performance. The scores are combined and compared with scores achieved by the same individual in previous tests. It has been found that this test provides a fairly reliable indication of drug or alcohol impairment, but a still better performance test is required.